How to sort an array of ints using a custom comparator?

Question

I need to sort an array of ints using a custom comparator, but Java's library doesn't provide a sort function for ints with comparators (comparators can be used only with objects). Is there any easy way to do this?

Answer 1

If you can't change the type of your input array the following will work:

final int[] data = new int[] { 5, 4, 2, 1, 3 }; final Integer[] sorted = ArrayUtils.toObject(data); Arrays.sort(sorted, new Comparator<Integer>() {     public int compare(Integer o1, Integer o2) {         // Intentional: Reverse order for this demo         return o2.compareTo(o1);     } }); System.arraycopy(ArrayUtils.toPrimitive(sorted), 0, data, 0, sorted.length); 

This uses ArrayUtils from the commons-lang project to easily convert between int[] and Integer[], creates a copy of the array, does the sort, and then copies the sorted data over the original.